Struct cranelift_codegen::ir::instructions::OpcodeConstraints

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pub struct OpcodeConstraints { /* private fields */ }

Expand description

Value type constraints for a given opcode.

The InstructionFormat determines the constraints on most operands, but Value operands and results are not determined by the format. Every Opcode has an associated OpcodeConstraints object that provides the missing details.

Implementations§

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impl OpcodeConstraints

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pub fn use_typevar_operand(self) -> bool

Can the controlling type variable for this opcode be inferred from the designated value input operand? This also implies that this opcode is polymorphic.

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pub fn requires_typevar_operand(self) -> bool

Is it necessary to look at the designated value input operand in order to determine the controlling type variable, or is it good enough to use the first return type?

Most polymorphic instructions produce a single result with the type of the controlling type variable. A few polymorphic instructions either don’t produce any results, or produce results with a fixed type. These instructions return true.

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pub fn num_fixed_results(self) -> usize

Get the number of fixed result values produced by this opcode. This does not include variable_args produced by calls.

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pub fn num_fixed_value_arguments(self) -> usize

Get the number of fixed input values required by this opcode.

This does not include variable_args arguments on call and branch instructions.

The number of fixed input values is usually implied by the instruction format, but instruction formats that use a ValueList put both fixed and variable arguments in the list. This method returns the minimum number of values required in the value list.

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pub fn result_type(self, n: usize, ctrl_type: Type) -> Type

Get the value type of result number n, having resolved the controlling type variable to ctrl_type.

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pub fn value_argument_constraint(
    self,
    n: usize,
    ctrl_type: Type
) -> ResolvedConstraint

Get the value type of input value number n, having resolved the controlling type variable to ctrl_type.

Unlike results, it is possible for some input values to vary freely within a specific ValueTypeSet. This is represented with the ArgumentConstraint::Free variant.

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